1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method for processing digital image data, and particularly to an image processing apparatus and an image processing method for processing digital image data to which additional data such as a copyright ID and user ID are appended.
2. Description of the Related Art
An additional data embedding technique is used to embed additional information in digital image data in superimposed form. Recently, there is a brisk movement to utilize the additional data embedding technique for the purpose of copyright protection of digital products such as still image data and the like, or prevention from illegal duplication thereof. Also, there is another tendency to utilize the additional data embedding technique for the purpose of integrating specific electronic image data and other digital image data related thereto, or private communications.
When the additional data embedding technique is used for the purposes described above, image data should be distributed after embedding additional data such as a copyright ID, user ID, or any identification data in the image data such that it is visually inconspicuous. There are several known techniques for embedding such additional data. Examples include a technique of embedding additional data by superimposing noise signals representing additional data in image data (refer to Japanese Published Unexamined Patent Application No. Hei 9-509795), and a technique of embedding additional data by subjecting image data to Fourier transform and manipulating conversion coefficients of concentric areas indicating identical frequencies on a frequency space (refer to Japanese Published Unexamined Patent Application No. Hei 10-51650).
These additional data embedding techniques are primarily used to prevent electronic illegal duplication or illegal use of electronic image data. Therefore, additional data is embedded in image data such that images based on the electronic image data are displayed on a display without degradation of image quality. Consequently, once electronic image data has been printed by a printer, it is difficult to detect additional data embedded in the image data from images formed on paper after printing.
Accordingly, even if additional data is embedded in electronic image data, since the additional data cannot be recognized from printed images, the printed images might be duplicated and distributed. This results in infringement on the copyright of the creator of the electronic image data. In order that additional data can be recognized from printed images, it is conceivable to embed the additional data in electronic image data to be distributed with a higher embedding strength. In this case, however, there is a problem in that the electronic image data could be displayed on a display with great degradation of image quality.
On the other hand, as a related art of embedding additional data in printed images, there is disclosed in Japanese Published Unexamined Patent Application No. Hei 6-113107 a technique of embedding additional data in printed images by superimposing patterns having positive and negative amplitudes in images in yellow ink.
There is disclosed in Japanese Published Unexamined Patent Application No. Hei 10-290312 a technique by which, when watermark data embedded in digital image data is detected, watermark data accumulated in a watermark data detection unit is multiplied by a constant to almost the same degree as a dynamic range of the image data and the result is added to the image data to be restored, which is sent to a printing unit.
However, if this technique is applied, as described in Japanese Published Unexamined Patent Application No. Hei 10-290312, images wholly different from the original images may be output from the printing unit. Accordingly, there arises a problem that the quality of printed images is heavily degraded. This poses a great problem in an attempt to sell images to users and give the users permission to print out them with high quality.
The present invention has been made in consideration of the above-described problems and its object is to provide an image processing apparatus and an image processing method which enable additional data to be embedded in electronic image data such that it can be detected without failure from printed images without degradation of image quality.
An image processing apparatus according to the present invention comprises: an additional data recognition part for recognizing that first additional data representing additional information is appended to image data from which to form images; and an appending part, when it is recognized by the additional data recognition part that the first additional data is appended, for appending second additional data representing additional information to the image data, wherein the additional information is extractable from formed images.
In the image processing apparatus having the above-described configuration, an additional data recognition part gets image data from which to form images, and determines whether or not first additional data representing additional information such as copyright ID information is appended to the image data. If the additional data recognition part recognizes that the first additional data is appended, the appending part receives the recognition result and appends second additional data representing additional information extractable from formed images to the image data to output the image data.
Since the present invention appends as additional data, to image data, second additional that is unrecognizable to human eyes from formed images, the above-described problem of Japanese Published Unexamined Patent Application No. Hei 10-290312 is solved.